Understanding the Bi-directional Relationship between Mental Illness and Cardiovascular Disease
Restricted (Penn State Only)
- Author:
- Dhingra, Radha
- Graduate Program:
- Epidemiology (PhD)
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 17, 2023
- Committee Members:
- Douglas Leslie, Program Head/Chair
Erika F H Saunders, Outside Unit & Field Member
Vernon Chinchilli, Major Field Member
Jeffrey Yanosky, Major Field Member
Duanping Liao, Chair & Dissertation Advisor
Laila Al-Shaar, Special Member
Member Committee, Special Member - Keywords:
- epidemiology
mental illness
depression
PHQ-9
PHQ-9 trajectory
cardiovascular disease
hypertension
diabetes
dyslipidemia
electronic health record
measurement-based care - Abstract:
- With individual economic burdens ranging in billions of dollars, depression and cardiovascular disease (CVD) are the leading causes of disability in the U.S. In 2019, 21.0 million and 18.2 million U.S. adults suffered from depression and CVD, respectively. Coronary heart disease, stroke, heart failure, and transient ischemic attacks, also called mini-strokes, are the most common CVDs. Well-known cardiovascular (CV) risk factors, such as obesity, hypertension, diabetes, dyslipidemia, and smoking, are the leading contributors to the premature morbidity and mortality associated with CVD. Increasingly, mental illnesses, such as depression and anxiety disorders, are being recognized as independent CV risk factors. In fact, chronic depression and anxiety have been identified as leading contributors to CVD-related healthcare costs. Due to shared behavioral and biological risk factors, a bi-directional relationship has been hypothesized between depression and CVD. Indeed, CVD is the leading cause of premature mortality among individuals with mental illness. Prior studies that examined the relationship between mental illness and CVD were limited by reliance on inconsistent, self-reported definitions of psychiatric and CVD outcomes, differences in study designs, broad measurements for psychological distress, and use of research-oriented questionnaires, such as the Center for Epidemiologic Studies Depression Scale to ascertain depression. Given the rising burden of mental illness and CV globally and in the U.S., it is imperative to corroborate existing evidence on the relationships between the two conditions using data sources that have improved sensitivity and specificity for defining CVD and depression outcomes. Furthermore, depression and anxiety disorders are modifiable risk factors, and their timely identification and treatment could prevent CV disease/risk factor onset and progression. In fact, one of the recommendations by the American Heart Association (AHA) is to evaluate the need for routine depression screening in primary care practices among individuals with CVD and CVD risk factors. This dissertation aimed to further understand the bi-directional relationship between mental illness and CVD using two data sources: i) electronic health records (EHR) of the Penn State Psychiatry Clinical Assessment and Rating Evaluation System (PCARES) Registry, a patient registry of 3556 individuals with mental illness, and ii) the National Health and Nutrition Examination Survey (NHANES) data, a representative sample of the U.S. general population. There were significant advantages to using EHR data for our research question. First, EHR data are clinician-documented data, which is highly sensitive and specific in determining diagnostic and therapeutic information compared to the low-sensitivity, self-reported data used in most prior studies; second, EHR data reflect patient behavior and clinical decision-making in real-world settings, possibly increasing the validity of our findings; third, EHR data provide information concerning individuals with multiple comorbidities, including mental illness, who may be underrepresented in epidemiological studies; and finally, EHR data is collected and available in near real-time, minimizing patient recall bias, a type of systematic error introduced when patients cannot accurately remember details of their medical history. The specific aims for our research project were: i) to compare CVD and CVD risk factor burden in the PCARES sample to the U.S. general population sample; ii) to investigate the relationship between baseline CV disease/risk factor burden and depression symptom severity in both the PCARES and NHANES samples; and iii) to assess the impact of baseline depression symptom severity on long-term trends of CVD metabolic biomarkers, such as glucose and lipid labs, among individuals with baseline diabetes and dyslipidemia in the PCARES sample. Key findings from our project showed that the PCARES sample, which comprises individuals with mental illness, had a significantly higher burden of CVD and CV risk factors compared to the U.S. general population, even after accounting for age, race, and gender differences between the two samples. We also observed that among the U.S. general population, not only was CV risk factor burden associated with worsened depression symptoms, but the number of CV risk factors was also associated with the extent of the depression symptoms. Similarly, in the PCARES sample, baseline CV disease/risk factors predicted a worsening depression symptom course over a one-year follow-up period. Lastly, we found long-term increases in glucose levels in individuals with moderate-to-severe depression symptoms and diabetes in the PCARES sample. Our finding of worsening longitudinal depression symptom trajectory in individuals with baseline CV disease/risk factors substantiates evidence for AHA’s recommendation to introduce regular depression screening in primary care practices. Regular assessment and monitoring of depression is particularly important among individuals with CVD, as a significant percentage of mental health care services in the U.S. are provided by primary care physicians and not mental health specialists. The U.S. National Health Interview Survey reported that participants with anxiety or depression and no past-year visit with a mental health professional had 62% higher risk of all-cause mortality compared to participants who had such a visit. In addition to support for regular depression screening in primary care practices for individuals with CVD, our findings have broader implications for various healthcare domains: i) for healthcare systems, we corroborate existing evidence regarding the long overdue need for integrated mental and physical healthcare services; ii) for healthcare professionals, we recommend addressing preclinical CVD risk factors (e.g., suboptimal diet and physical inactivity) among psychiatric patients; iii) for researchers, we highlight the need to bridge pathways between mental and physical health to address health disparities among vulnerable populations; and iv) for policy-makers, we urge special attention to individuals with mental illness in cardiovascular health improvement programs.